The present invention relates to the design of compressor valves and in particular to a compressor valve which has a simplified design, reduced cost, improved reliability and reduced clearance volume of the valve and hence increased compressor capacity. Specifically, the invention allows the use of an easily manufactured flat biasing spring member to maintain the valve plate member in its closed position.
Suction or pressure valves for use in a piston compressor are usually constructed with a valve seat having concentrically arranged, ring-shaped, fluid flow passages. A plate member having concentrically arranged ring members in juxtaposed relationship with the fluid passages normally seals the passages and prevents fluid from passing therethrough. A spring plate rests upon the plate member and spring members bias the plate member against the fluid passages to maintain a sealed relationship and prevent fluid from passing therethrough. When the pressure becomes sufficiently great in the passages, the plate member is forced outwardly against the spring plate and opens the fluid flow passages allowing the fluid to pass through the valve. When the pressure decreases sufficiently, the spring members force the plate member against the passages which once again maintains them in a sealed relationship. Such spring members may include a coiled spring as disclosed in U.S. Pat. Nos. 4,307,751 and 4,184,508, a curved spring plate as disclosed in U.S. Pat. No. 3,945,397 or a flat spring which also serves as the plate member as disclosed in U.S. Pat. No. 4,164,238.
The coiled springs disclosed in U.S. Pat. Nos. 4,307,751 and 4,184,508 are unsatisfactory because they require a greater space or volume in the valve itself, thus decreasing the compressor capacity. It would be desirable to make the valve considerably smaller in order to increase compressor capacity. The curved spring plates as disclosed in U.S. Pat. No. 3,945,397 are unsatisfactory because the resilient arms of the plate must be bent or curved in a fixed deformable shape and the spring material must be bent in such a way that it is not stressed. It is considerably easier to make a flat spring. U.S. Pat. No. 4,164,238 uses such a flat spring but it is unsatisfactory since the spring is rigidly attached to the valve seat having the arcuate shaped fluid flow passages and is in fact the plate member for sealing these passages. The flat spring plate is rigidly attached to the valve seat at two locations. When sufficient pressure is provided in the fluid flow passages or ports, it tends to bend the flat plate about the attachment points to uncover the fluid flow ports and allow the fluid to pass through the valve. There is very little movement that can take place by bending the spring plate when it is rigidly attached to and forms the plate which seals the valve seat ports. Further, the passages are not uniformly uncovered and thus fluid flow through the passages is not uniform. Further, the spring plate material is dictated by its spring function precluding the use of desirable non-metallic plate materials.
The present invention overcomes the disadvantages of the prior art by providing a valve for a piston compressor which is smaller in volume than prior art valves because of its flat spring construction and which also has a movable plate member formed with flat concentric sealing members which seal corresponding ones of the fluid flow ports of the valve seat. The movable plate member is biased in that sealing position by the flat spring. The plate member is allowed to move axially toward the spring plate when sufficient pressure is developed in the fluid flow ports and thus bends or deforms at least part of the spring plate so that the fluid can move through the fluid ports. The spring plate is rigidly attached to a guard member in spaced relationship with the valve seat.
The plate member which seals the fluid ports of the valve seat has projections on the flat concentric sealing members which extend toward and contact finger-like arcuate projections on the spring plate. The spring fingers bias the plate member against the valve seat and thus seal the fluid flow ports. When sufficient pressure is applied in the fluid flow ports, the plate member is forced by the fluid pressure toward the spring member and the projections on the plate member cause the spring like fingers on the spring plate to bend or flex thus allowing the entire sealing plate member to move away from all of the fluid flow ports simultaneously and uniformly and allow the pressurized fluid to pass through the valve. When the pressure is reduced sufficiently, the spring like fingers pressing against the projections on the plate member force the plate member back to its original position against the valve seat and thus seal the fluid flow ports.
A hollow cylindrical spacer extends through an orifice in the plate member and contacts both the valve seat and the spring plate thus maintaining a fixed separation between the spring plate and the valve seat while simultaneously allowing the plate member to move away from the valve seat toward the spring plate. A guard member surrounds the spring plate, and the sealing plate member and is attached to the valve seat to hold the entire compressor valve together as an integral unit. Guide pins extend through arms in the guard plate, the spring plate and the plate member into orifices in the valve seat to align the spring plate and the plate member and prevent them from rotating with respect to the valve seat or each other.
An important aspect of this case is that the sealing plate member can be made of plastic. Plastic has the ability to resist impact fatigue, resist corrosion, tolerate dirt by embedding the particles without allowing fluid leakage and is light weight. Plastic can be injection molded to form the sealing plate members with the projections on one side thereof in a relatively economical manner. However, such molded plastic plate must have flat sealing surfaces in order to properly seal the fluid passages in the valve seat. Because of the construction of this valve with a flat spring plate and the novel plastic sealing plate, the valve is smaller than those in the prior art which enables a smaller compressor to do the same job.
Thus it is an object of the present invention to provide and improve the movable sealing plate member for a compressor valve with the sealing plate member being formed of plastic and having a plurality of flat sealing members for juxtaposed sealing engagement with a like plurality of fluid passage ports in the valve seat member and at least two projections formed on the sealing members of the plate member and extending outwardly from the plate member in a direction away from the valve seat member for receiving a spring member urging sealing members of the plate member against and sealing the fluid passage ports in the valve seat member.
It is also an object of the present invention to provide the movable plate member with a plurality of arcuate concentric rings forming the flat sealing members and having projections on one side thereof and including means for enabling the plate to move axially away from the valve seat member to uncover the fluid passage ports.
It is still another object of the present invention to provide a flat spring plate in juxtaposed abutting relationship with a sealing plate member which has at least two projections formed on sealing members and with at least one spring finger extending from a central portion of said flat spring plate and resting on a corresponding one of the projections on the plate member sealing members for holding the plate in sealing engagement with the fluid passage ports and enabling the plate member to be forced against the spring member to bend the spring fingers and uncover the fluid passage ports.
It is still another object of the present invention to provide at least two arms radially extending from the central portion of a spring plate with at least one spring finger extending arcuately from each of the arms to rest upon a corresponding one of the projections on the movable plate to bias the movable plate against and seal the fluid passage ports in the seat member.
It is yet another object of the present invention to provide a plate valve for a compressor, the valve comprising a seat member having fluid passage ports therein, a movable plate member in contact with and controlling the flow of fluid through the ports, the plate member having at least one integrally formed projection on one side thereof, and a flat stationary spring plate having spring fingers thereon to contact the plate member projection to bias the plate member against and seal the fluid passage ports.